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Python: Why to Use __lt__ Instead of __cmp__

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th?q=  lt   Instead Of   cmp   - Python: Why to Use __lt__ Instead of __cmp__

Python is a popular programming language known for its simple syntax and versatility. In Python, there are two ways to define comparisons between objects – using the __lt__ method and the __cmp__ method. While both methods achieve the same goal, the former is preferred over the latter for several reasons. If you’re curious to know why, read on!

When it comes to defining object comparisons in Python, the __lt__ method is more intuitive and easier to use. It simply returns a boolean value indicating whether the current object should be considered less than the other object being compared. On the other hand, the __cmp__ method requires the programmer to manually code all the logic for the different comparison scenarios (less than, equal to, greater than, etc.) making it more cumbersome to use.

In addition to being more straightforward, using the __lt__ method also leads to more concise and readable code. Since the method only needs to return a boolean value, there is no need to write extensive if-else statements to handle various comparison cases. This makes the code cleaner and easier to maintain.

So the next time you’re writing code that involves object comparisons in Python, consider using the __lt__ method instead of the __cmp__ method. Not only is it simpler and more natural to use, but it also results in code that is more efficient and easier to understand. Trust us, your fellow developers (and your future self!) will thank you for it.

th?q=  lt  %20Instead%20Of%20  cmp   - Python: Why to Use __lt__ Instead of __cmp__
“__lt__ Instead Of __cmp__” ~ bbaz


Python, a high-level programming language, is known for being easy to read, write and maintain but don’t be fooled by its simplicity, it has a lot of power and robustness under the hood. In Python, there are many ways to compare objects, and in this article, we will focus on the comparison between __lt__ and __cmp__.


The __lt__ method is called when comparing two objects using the less-than operator (<). The method should return True if the object on the left is strictly less than the object on the right, and False otherwise. Here is a simple example:

“`pythonclass Person: def __init__(self, name): = name def __lt__(self, other): return < other.nameperson1 = Person(Alice)person2 = Person(Bob)if person1 < person2: print(Alice is less than Bob)```

Advantages of using __lt__

The __lt__ method is more straightforward than __cmp__, and it is also faster since it only needs to compare two objects at a time instead of a tuple of objects. It provides better performance in sorting sequences, which is an essential operation in programming.


The __cmp__ method is used to compare two objects and returns an integer value based on the comparison outcome. If the objects are equal, it returns 0; if the first object is greater than the second one, it returns 1, and if it is less than the second object, it returns -1. Here is an example:

“`pythonclass PersonWithCmp: def __init__(self, name): = name def __cmp__(self, other): if == return 0 elif < return -1 else: return 1person1 = PersonWithCmp(Alice)person2 = PersonWithCmp(Bob)if person1 < person2: print(Alice is less than Bob)```

Disadvantages of using __cmp__

The main disadvantage of using __cmp__ is that it takes up more memory since it needs to generate a tuple of objects to compare them. Also, the method is slower since it needs to create a tuple on every comparison, making it unsuitable for big data structures.

Comparison Table

Method Advantages Disadvantages
__lt__ Fast and straightforward, better performance in sorting sequences No disadvantages
__cmp__ Can be used to compare in a different way than __lt__, provides compatibility with previous Python versions Slower, high memory usage for big data structures


After discussing the advantages and disadvantages of __lt__ and __cmp__, it is clear that __lt__ is the preferred method for comparing objects in Python. It is faster, simpler, and more memory-efficient, which makes it the best choice for most programming tasks.

Thank you for reading this article about the benefits of using __lt__ instead of __cmp__ in Python. We hope that it has been informative and useful for your own coding projects. By implementing this method, you can avoid the risks and errors associated with the older method and enjoy improved functionality and efficiency.

Python is a versatile and powerful programming language that can be used for a wide range of tasks and applications. Whether you are a beginner or an experienced programmer, learning about these different methods and functions can help you to become more efficient and effective in your work.

If you have any questions, comments, or suggestions about this topic or any other related to Python, we encourage you to continue exploring and learning more. There are many online resources and communities that can provide you with support, advice, and inspiration as you develop your skills and knowledge in this exciting field.

People also ask:

  1. Why to use __lt__ instead of __cmp__?


  • The reason why you should use __lt__ instead of __cmp__ is that __cmp__ has been deprecated in Python 3.0 and later versions. The main difference between the two is that __cmp__ returns an integer value (-1, 0, or 1) whereas __lt__ returns a Boolean value (True or False).
  • Using __lt__ makes your code more readable and easier to understand as it compares two values and returns a Boolean value indicating whether one is less than the other.
  • Another advantage of using __lt__ is that it allows for more flexible sorting of objects. You can define a custom comparison function that compares objects based on any criteria you want.